Electrochemical battery pack with reduced magnetic field emission and corresponding devices
A battery pack with reduced magnetic field emissions includes a plurality of cells (1301,1302) coupled electrically together by a first electrical conductor (1307) and a second electrical conductor (1308). The first electrical conductor (1307) couples positive terminals (1305,1306) to a terminal block (1311), while the second electrical conductor (1308) couples the negative terminals (1303,1304) to the terminal block (1311). Each cell (1301,1302) contains an asymmetrical internal electrode construction (1313,1314) having electrical tabs (502,503) coupled to a cathode and anode. The cells (1301,1302) can be arranged with their corresponding asymmetrical internal electrode constructions (1313,1314) oriented in different directions to reduce magnetic field emissions. The first electrical conductor (1307) and second electrical conductor (1308) can be routed such that magnetic fields generated by discharge currents tend to reduce other magnetic fields produced by other components within the battery pack.
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This application is related to commonly assigned U.S. application Ser. No. 12/766,023, filed Apr. 23, 2010, which is incorporated by reference for all purposes.
BACKGROUND1. Technical Field
This invention relates generally to batteries having electrochemical cells, and more particularly to a battery pack having construction features that deliver reduced magnetic field emissions during discharge.
2. Background Art
The world is rapidly becoming portable. As mobile telephones, personal digital assistants, portable computers, tablet computers, and the like become more popular, consumers are continually turning to portable and wireless devices for communication, entertainment, business, and information. Each of these devices owes its portability to a battery. The electrochemical cells operating within a battery allow these devices to slip the surly bounds of having to be tethered to a wall outlet, thereby providing the user with freedom and mobility.
The primary job for the electrochemical cells working within the battery pack is to deliver energy. Rechargeable batteries are configured to selectively store energy as well. Magnetic field emissions associated with a battery pack are generally not a design consideration. By way of example, when a battery pack is used to power a typical electronic device, the magnetic field emissions therefrom may not be significant enough to affect the operation of that device. However, in some applications, the magnetic field emission can be a design issue.
There is thus a need for a battery pack having reduced magnetic emission.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
DETAILED DESCRIPTION OF THE INVENTIONEmbodiments of the invention are now described in detail. Referring to the drawings, like numbers indicate like parts throughout the views. As used in the description herein and throughout the claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise: the meaning of “a,” “an,” and “the” includes plural reference, the meaning of “in” includes “in” and “on.” Relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, reference designators shown herein in parenthesis indicate components shown in a figure other than the one in discussion. For example, talking about a device (10) while discussing figure A would refer to an element, 10, shown in figure other than figure A.
Electrochemical cells, such as those used in lithium-ion cells, are generally constructed with stacked electrode layers and their associated metal tabs that are wound together in a “jellyroll configuration.” These layers, which can include an anode, an electrical insulator or “separator,” and a cathode, are wound together and then enclosed in a metal housing. While the housing can be manufactured from any of a number of materials, it is often manufactured from steel, aluminum or aluminum alloy. The housing is then filled with an organic electrolyte. This type of construction can create loops or other current paths that generate different levels of magnetic field emissions, depending on its detailed design, when the battery pack is discharging. These fields can be unsuitably large in some applications. These magnetic fields can be especially troublesome when the discharge current is characterized by audio-frequency pulses, as in some mobile phone applications. Embodiments of the present invention provide battery pack constructions using pluralities of cells where the constructions are configured to deliver reduced magnetic field emissions.
For example, in one embodiment a plurality of cells is coupled together within the battery pack with electrical conductors. The electrical conductors may be configured as metal strips, substrate traces, or other current conductors. Each cell within the battery pack includes therein an asymmetrical internal electrode and tabs connection construction. The asymmetrical internal electrode construction arises due to the wound electrodes within the cell. These wound electrodes are asymmetrical when viewed in cross section. In accordance with embodiments of the invention, these cells having asymmetrical internal configurations can be physically arranged and oriented within a battery pack to mitigate magnetic field emissions during discharge operations. Where the cells are rechargeable cells, embodiments of the invention work to reduce magnetic field emissions during charging operations as well.
In one embodiment, adjacent cells are arranged such that their corresponding asymmetrical internal electrode constructions are oriented in different or opposite directions with respect to each other. For example, where two cells have housings with minor faces abutting, one cell can be configured differently from its adjacent cell such that one cell's internal electrode structure is oriented differently. When viewed in cross section, the different orientation causes the internal electrode structure of one cell to appear as a rotation, mirror image, or other transformation of that of an adjacent cell. This results in the internal tabs being physically oriented “out of phase” with each other, thereby reducing overall magnetic field emissions. In addition to cell orientation, electrical conductors within the battery pack that connect the cells to the external terminals can be routed so as to mitigate magnetic field emissions from other electrical conductors, tabs within the cells, or combinations thereof.
Illustrating by example, in one embodiment an electrochemical cell, such as a lithium-ion or lithium-polymer rechargeable cell, is arranged within a battery pack with its internal electrode structure oriented differently from that of its neighbors. When the cells are arranged side-by-side, the negative terminals can be positioned opposite one another by rotating each adjacent cell by 180 degrees. Electrical conductors connecting these negative terminals can then pass between or over major faces of the housings of each cell. Where the housings are coupled to an electrode carrying a positive charge, this arrangement leads to a reduction in the magnetic “noise” generated by the battery pack.
In another embodiment where cells are stacked, the negative terminals can additionally be positioned such that those of adjacent cells are 180 degrees out of phase. Electrical conductors connecting these negative terminals can then pass between or over the housings of the cells that carry positive charge, thereby mitigating emitted magnetic fields during discharge. Further, in either the side-by-side or stacked configurations, the cells may be “flipped” such that the electrical tabs within each cell are oriented differently, thereby further reducing the magnetic field emissions. Numerous examples of different configurations will be provided in the discussion of
Referring now to
The electrode 100 of
Disposed atop first layer 118, is a current collecting layer 120. The current collecting layer may be fabricated of any of a number of metals or alloys known in the art. Examples of such metals or alloys include, for example, nickel, aluminum, copper, steel, nickel plated steel, magnesium doped aluminum, and so forth. Disposed atop the current collection layer 120 is a second layer 122 of electrochemically active material.
The electrochemical cell stores and delivers energy by transferring ions between electrodes through a separator. For example, during discharge, an electrochemical reaction occurs between electrodes. This electrochemical reaction results in ion transfer through the separator, and causes electrons to collect at the negative terminal of the cell. When connected to a load, such as an electronic device, the electrons flow from the negative pole through the circuitry in the load to the positive terminal of the cell. This is shown in circuit diagrams as current flowing from the cathode to the anode.
When the electrochemical cell is charged, the opposite process occurs. Thus, to power electronic devices, these electrons must be delivered from the cell to the electronic device. This is generally accomplished by coupling conductors, such as conductive foil strips, sometimes referred to colloquially as “electrical tabs” to the various layers. Such tabs are shown in
Referring now to
A first tab 280 is coupled to one electrode 240, while a second tab 290 is coupled to another electrode 260. These tabs 280,290 can be coupled to the current collectors of each electrode 240,260.
The electrodes 240 and 260 are arranged in stacked relationship, with the tabs 280,290 being disposed on opposite edges of the stack. Thereafter, the stack is rolled into a roll 270, sometimes referred to as a “jellyroll,” for a subsequent insertion into an electrochemical cell housing. The housings are generally oval, but can also be rectangular, or circular in cross section as well. The housings have an opening that is sealed when the roll 270 is inserted.
This rolling process creates an asymmetrical internal electrode construction. As shown in
Turning now to
In the illustrative embodiment of
In alternate embodiments, the tabs 301,302 can be connected to a terminal block 306 rather than to the lid 303 and housing 322. The terminal block 306 provides a convenient way for both the positive terminal and negative terminal to reside on a common end of the cell 300. Note that the terminal block 306 of
Regardless of whether the cell 300 employs a lid-based construction or a terminal block-type construction, either embodiment can emit a relatively large amount of magnetic field noise when in operation. This noise is measured in dB A/m, and increases with increasing current. Further, when the current is pulsed, as is the case when a cell is servicing a GSM device such as a mobile telephone, the noise can be exacerbated. Embodiments of the present invention work to mitigate this magnetic field emission with strategic placement and orientation of cells and electrical conductor wiring within the battery pack.
Turning to
The electrical tabs 411,412 are arranged in a non-symmetrical configuration within the housing 401 such that a first electrical tab 411 is centrally disposed within the housing 401 and a second electrical tab 412 is peripherally disposed within the housing 401. The electrical tabs 411,412 couple terminals 413 disposed outside the cell 400 to the anode and the cathode of the electrode construction.
A label 407 is placed on the housing 401 when the cell construction is complete. As most manufacturers build cells with uniform, controlled processes, it is frequently the case that an orientation of the asymmetrical internal electrode construction 410 can be determined by identifying upon which side the label 407 is disposed. For example, in
For simplicity of discussion, the various embodiments shown in remaining figures will refer to the label side of a cell and a non-label side of the cell. This reference presumes a common orientation of the asymmetrical internal electrode constructs therein relative to a placement of the label, such that reference to “the label side” refers to one orientation of the asymmetrical internal electrode construction and reference to “the non-label side” refers do a different orientation of the asymmetrical internal electrode construction. It should be clear that these references are intended only to identify the electrode orientations and to help facilitate a description of embodiments of the invention. Operation and benefits of embodiments of the invention are in no way dependent upon the location of the label. Further, other ways of identifying the orientation of the asymmetrical internal electrode construction will be readily available to those of ordinary skill in the art having the benefit of this disclosure.
This is illustrated in
In
Turning now to
The embodiment of
Turning now to
As shown in
Turning now to
Turning now to
As with
Turning now to
Turning now to
The embodiments of
Turning now to
Further, it should be noted that the lengths of the electrical conductors are non-intuitive in that they are generally longer than necessary and use more material than necessary. However, the paths traveled by the electrical conductors are strategic and are specifically designed to mitigate magnetic fields. For example, by causing an electrical conductor to pass across a major face of a cell, and more specifically across a major face atop an internal tab, the electrical conductor can be used to cancel or reduce the magnetic field emitted by the tab when the current in the tab and conductor flow in opposite directions. The embodiments of
Beginning with
As shown in
The first electrical conductor 1307 and second electrical conductor 1308, which may be made from flexible metal for example, pass about the ends of the cells 1301,1302 en route to the terminal block 1311, thereby offering relatively short path lengths. In one embodiment, these path lengths are configured such that one or both of the first electrical conductor 1307 or the second electrical conductor 1308 are arranged to reduce magnetic field emissions from one or more of the other electrical conductor, the electrode assemblies, the tabs within the cells 1301,1302, or combinations thereof by directing opposite currents to flow in proximate relationships.
For example, in the illustrative embodiment of
Turning now to
As shown in the sectional view, the second electrical conductor is disposed between electrical tabs 1431,1432. Since the cells 1401,1402 are oriented out of phase with respect to each other, the discharge current flowing in the second conductor 1408 will be opposite the discharge current flowing in one of the two tabs 1431,1432. Thus, by configuring the second conductor 1408 to pass atop about this “opposite current” tab disposed within one of the two adjacent cells 1401,1402, the current flowing in the conductor 1408 will be opposite in direction from that flowing in the tab, thereby reducing the magnetic field emissions. Additionally, with the corresponding asymmetrical internal electrode constructions 1413,1414 oriented in opposite directions, discharge currents 1415,1416 flowing through the corresponding asymmetrical internal electrode constructions 1413,1414 flow in opposite directions, thereby further mitigating magnetic field emissions.
Turning now to
A first electrical conductor 1507 is coupled to each negative terminal 1503,1504. The first electrical conductor 1507 passes between the cells 1501,1502. A second electrical conductor 1508 couples the positive terminals 1505,1506, and is configured to pass across a major face of the cells 1501,1502. In this illustrative embodiment, electrical conductor 1508 is configured to pass across both the label side 1509 of the first cell 1501 and the non-label side 1510 of the second cell 1502. Insulating material 1550,1551 can be used to keep the electrical conductors 1507,1508 from shorting together or to the housing of each cell 1501,1502. This electrical conductor routing reduces magnetic field emissions from the layer.
Cell 1502 is rotated 180 degrees out of phase with respect to cell 1501. Accordingly the positive terminal 1506 of cell 1502 is disposed on the opposite end of the layer from positive terminal 1505. The corresponding asymmetrical internal electrode constructions 1513,1514 oriented in opposite directions, discharge currents 1515,1516 flowing through the corresponding asymmetrical internal electrode constructions 1513,1514 flow in opposite directions, thereby further working to reduce magnetic field emissions.
Turning now to
A first electrical conductor 1607 is coupled to each negative terminal 1603,1604. Rather than being coupled in a straight line between each negative terminal 1603,1604, the first electrical conductor 1607 is configured in a loop 1660 having a width 1660 greater than a distance 1662 between negative terminal 1603 and negative terminal 1604. This path, which is disposed atop an insulating layer 1650, works to reduce magnetic field emissions.
A second electrical conductor 1608 couples the positive terminals 1605,1606, and is configured to pass about a minor face of cell 1602. Cell 1602 oriented in-phase with respect to cell 1601, so the positive terminals 1605,1606 are disposed on a common side of the layer.
Turning now to
A first electrical conductor 1707 is coupled to each negative terminal 1703,1704. As with
Turning now to
The embodiment of
A first electrical conductor 1807 is coupled to each negative terminal 1803,1804. A second electrical conductor 1808 is coupled to each positive terminal 1805,1806. In this illustrative embodiment, the second conductor 1808 is configured to pass across a major face of each cell 1801,1802 in relatively close proximity to the first electrical conductor 1807. This close relationship facilitates a magnetic field 1881 generated by discharge current in the first electrical conductor 1807 to be substantially opposite in magnitude and direction from a magnetic field 1882 generated by discharge current in the second electrical conductor 1808. These fields tend to cancel, thereby reducing the overall magnetic field emissions.
Turning now to
The electrical conductors 1907,1908 shown in
Turning now to
A first electrical conductor 2007 is coupled to each negative terminal 2003,2004. Rather than being coupled in a straight line between each negative terminal 2003,2004, the first electrical conductor 2007 is configured in a loop 2060 across a major face of cell 2001 such that a leg 2027 of the first electrical conductor 2007 passes atop an electrical tab 2034 disposed within cell 2001. In this configuration, a discharge current flowing in the electrical tab 2031 will be in an opposite direction of a discharge current flowing in the electrical conductor 2007. Accordingly, a magnetic field 2081 generated by discharge current in the first electrical conductor 2007 will be opposite in direction from a magnetic field 2082 generated by discharge current in tab 2031. These opposing fields reduce the overall magnetic field emissions. The first electrical conductor 2007 passes along a layer of insulation 2050 in this illustrative embodiment.
Turning now to
The orientation of the cells 2101,2102 in
Turning now to
As with
Turning now to
As shown in
Turning now to
To connect the negative terminals 2403,2404 to the terminal block 2411, a first electrical conductor 2407 passes across an insulation layer between each cell 2401,2402. A second electrical conductor 2408 couples each positive terminal 2405,2406 to the terminal block 2411.
Turning now to
A first electrical conductor 2507 is coupled to each negative terminal 2503,2504. Rather than being coupled in a straight line between each negative terminal 2503,2504, the first electrical conductor 2507 is configured in a loop 2560 having a width greater than a distance between the negative terminals 2503,2504. This path, which is disposed atop an insulating layer 2550, works to reduce magnetic field emissions. A second electrical conductor 2508 couples the positive terminals 2505,2506.
Turning now to
A first electrical conductor 2607 connects each negative terminal 2663,2664,2665 to a terminal block 2661, and runs about either side of a second electrical conductor 2608 connecting each positive terminal 2615,2616,2617 to the terminal block 2661. By passing the first electrical conductor 2607 about either side of the second electrical conductor 2608, magnetic fields about the second electrical conductor 2608 will be reduced by one leg of the first electrical conductor 2607, thereby reducing the overall magnetic field emissions of the layer.
The embodiments of
As shown in
As with previous embodiments, the electrical tabs, e.g., tabs 2931,2933, are disposed within the cells 2901,2902,2903 are arranged in a non-symmetrical configuration within a housing of each cell 2901,2902,2903. In
To mitigate electromagnetic interference with the electromagnetically sensitive device 2900, the techniques described with reference to
While the battery pack embodiments described above, for ease of discussion, have largely been shown as comprising cells, substrates, and terminal blocks, it will be clear to those of ordinary skill in the art having the benefit of this disclosure that embodiments of the invention may include additional components as well. For example, as shown in
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Thus, while preferred embodiments of the invention have been illustrated and described, it is clear that the invention is not so limited. Numerous modifications, changes, variations, substitutions, and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present invention as defined by the following claims. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims.
Claims
1. A battery pack with reduced magnetic emissions, comprising:
- a plurality of cells coupled electrically together, each cell comprising a housing having major and minor faces, and an asymmetrical internal electrode construction having electrical tabs coupled thereto, wherein at least two adjacent cells are arranged with their corresponding asymmetrical internal electrode constructions oriented in different directions;
- a first electrical conductor coupled to one of each positive terminal or each negative terminal of the at least two adjacent cells; and
- a second electrical conductor coupled to another of the each positive terminal or the each negative terminal of the at least two adjacent cells;
- wherein the first electrical conductor is arranged to reduce magnetic field emissions from one or more of the second electrical conductor or one or more of the electrical tabs during discharge of the of the battery pack.
2. The battery pack of claim 1, wherein the at least two adjacent cells are arranged in a layer such that minor faces of the at least two adjacent cells are abutting.
3. The battery pack of claim 2, wherein the layer comprises at least three adjacent cells.
4. The battery pack of claim 3, wherein a center cell of the at least three adjacent cells is arranged such that its asymmetrical internal electrode construction is opposite that of each adjacent cell.
5. The battery pack of claim 2, wherein the battery pack comprises a plurality of layers, each of the plurality of layers arranged such that a first major face of a first layer cell is adjacent to a second major face of a second layer cell.
6. The battery pack of claim 5, wherein the first layer cell and the second layer cell are arranged such that the asymmetrical internal electrode construction of the first layer cell is oriented opposite the asymmetrical internal electrode construction of the second layer cell.
7. The battery pack of claim 1, wherein the each cell further comprises a positive terminal and a negative terminal, wherein the positive terminal is disposed on an opposite side of the housing relative to the negative terminal.
8. The battery pack of claim 1, wherein the each cell further comprises a positive terminal and a negative terminal, wherein the positive terminal and the negative terminal are disposed on a common side of the housing.
9. The battery pack of claim 1, wherein one or more of the first electrical conductor or the second electrical conductor is configured to pass across a major face of one or more of the at least two adjacent cells.
10. The battery pack of claim 9, wherein the at least two adjacent cells are arranged in a layer, further wherein the one or more of the first electrical conductor or the second electrical conductor is configured in a loop having a width greater than a distance between a terminal of a first cell and a corresponding terminal of a second cell in the layer.
11. The battery pack of claim 9, wherein the one or more of the first electrical conductor or the second electrical conductor is configured to pass atop an electrical tab disposed within the one or more of the at least two adjacent cells, wherein a first current flowing in the electrical tab is opposite a second current flowing in the one or more of the first electrical conductor or the second electrical conductor during discharge of the battery pack.
12. A battery pack, comprising: a plurality of cells, each cell comprising:
- an anode;
- a cathode; and
- electrical tabs coupling terminals disposed outside the each cell to the anode and the cathode, respectively;
- wherein the electrical tabs are arranged in a non-symmetrical configuration within a housing of the each cell; and
- electrical conductors coupling the electrical tabs to a terminal block of the battery pack;
- wherein at least two adjacent cells are arranged such that, the electrical tabs coupled to one of cathodes or anodes of the at least two adjacent cells are disposed between the electrical tabs coupled to another of the one of cathodes or the anodes of the at least two adjacent cells; and
- wherein at least one of the electrical conductors is arranged such that current flowing in the at least one of the electrical conductors reduces current flowing in the at least one of the electrical tabs during discharge of the of the battery pack.
13. The battery pack of claim 12, wherein the housing is manufactured from steel, further wherein the one of cathodes or the anodes of the at least two adjacent cells comprises the anodes.
14. The battery pack of claim 12, wherein the housing is manufactured from aluminum, further wherein the one of cathodes or the anodes comprises cathodes.
1712026 | May 1929 | Clark |
4761352 | August 2, 1988 | Bakos et al. |
5300373 | April 5, 1994 | Shackle |
5986355 | November 16, 1999 | Rosen |
5991420 | November 23, 1999 | Stern |
6031923 | February 29, 2000 | Gnecco et al. |
6104021 | August 15, 2000 | Ogawa |
6546109 | April 8, 2003 | Gnecco et al. |
6574111 | June 3, 2003 | Gyenes et al. |
6808843 | October 26, 2004 | von During |
20020195990 | December 26, 2002 | Yang |
20030027039 | February 6, 2003 | Benson et al. |
20040038123 | February 26, 2004 | Hisamitsu et al. |
20050031945 | February 10, 2005 | Morita et al. |
20050069759 | March 31, 2005 | Shimamura et al. |
20070026318 | February 1, 2007 | Kishi et al. |
20070269685 | November 22, 2007 | Chu et al. |
20090029240 | January 29, 2009 | Gardner et al. |
20100316896 | December 16, 2010 | Van Schyndel et al. |
20110014942 | January 20, 2011 | Van Schyndel et al. |
20110020673 | January 27, 2011 | Van Schyndel |
20110111267 | May 12, 2011 | Van Schyndel |
20110262787 | October 27, 2011 | Maleki et al. |
20110262798 | October 27, 2011 | Neumann et al. |
2325932 | May 2011 | EP |
2000348757 | December 2000 | JP |
2007/220372 | August 2007 | JP |
2007220372 | August 2007 | JP |
WO-2010/003979 | January 2010 | WO |
- Patent Cooperation Treaty, International Search Report and Written Opinion of the International Searching Authority for International Application No. PCT/US2011/044921, Oct. 14, 2011, 12 pages.
- “PCT Search Report”, IA No. PCT/US2011/051749; Filed Sep. 15, 2011; Mailed Dec. 22, 2011.
- Giel-Barragan Ramos, Cecilia “PCT Search Report and Opinion”, Filed: Mar. 29, 2011 Priority Date: Apr. 23, 2010 Application: PCT?US2011/030258.
- Sanyo, “SGS t32 Cell”.
- Chan, Heng M., “NonFinal OA”, U.S. Appl. No. 12/766,023, filed Apr. 23, 2010; Mailed Jan. 30, 2013.
Type: Grant
Filed: Aug 9, 2010
Date of Patent: Feb 4, 2014
Patent Publication Number: 20120033845
Assignee: Motorola Mobility LLC (Libertyville, IL)
Inventors: Hossein Maleki (Lawrenceville, GA), Jerald A. Hallmark (Sugar Hill, GA)
Primary Examiner: Kenneth Douyette
Application Number: 12/853,055
International Classification: H01M 2/02 (20060101); H01M 2/22 (20060101); H01M 2/30 (20060101);